Right guys. Quite a weird problem here.
This has happened about 5 times since January and it scares the hell out of me every time. Last night, I was uninstalling a few steam games when Windows started to really chug, I mean really chug (about 10 second delay) and then just powered off. And when I would start her up, it wouldn't even boot, the fans would start and after about 2 seconds it would turn itself off and then on again doing the same thing each time. The only way to stop the cycle is to power off at the back. After about an hour of leaving it off, it boots normally again.
At first I thought it was the CPU overheating but if you take a look at the attached image, it's hovering at 40. Is that too hot?
(PS. I have noticed it's happened a few times after physically moving the entire tower)
EDIT: Just checked CPU-Z and it says my CPU is running at 3.8Ghz...I have no idea how to overclock and I didn't even think you could on the non-k series?
Either a power supply or motherboard problem. Probably the later. Have you tried updating the BIOS?
Your CPU is definitely not hot at all. If it were hovering at 70 degrees Celsius, I would be worried.